The development of diagnostic systems to assess and classify persons with communicative disorders, particularly etiologic systems leading to molecular genetics studies, is a key research target of NIDCD (National Strategic Research Plan, 1993). This research program is specifically concerned with these goals for the estimated 3 percent - 8 percent (approximately 4.8 million) children in this country with speech disorders of unknown origin. The research plan for the next period has three specific aims: to validate a phenotype marker for a genetically transmitted subtype of child speech disorders, to cross-validate a descriptive-explanatory model relating otitis media with effusion (OME) and hearing loss from 6-18 months to speech-language deficits at ages 3-6, and to explicate acoustic-phonetic correlates of reduced intelligibility in children with histories of significant OME. A total of 15 data sets will use speech information from 2,773 children from clinical-research facilities in six states. Project I: Speech-Genetics Studies has three project strands: (a) an epidemiologic study to estimate the prevalence of speech delay in kindergarten children, providing liability estimates for behavioral and molecular genetics research; (b) cross-sectional studies to test the optimum phenotype marker for speech delay in genetics studies-a broad- domain (core verbal trait disorder) marker using measures of phonological processing (i.e., phonological awareness) or a narrow- domain marker based on alternative productive speech metrics; and (c) longitudinal studies to determine whether normalization of speech disorder is associated with familial aggregation, with implications for genetic versus environmental regulation. Collaborative molecular genetics studies at three sites will test the alternative phenotypes. Project II: Speech-Otitis Media Studies has five project strands: (a) statistical modeling studies to identify sources of variance in unintelligibility in relation to OME, hearing loss, and speech-language variables; (b) acoustic correlate studies to describe and explicate acoustic contrastivity features associated with OME and lowered intelligibility; (c) structural equation modeling studies to characterize how OME and hearing loss at 6-18 months moderate and mediate later speech delay; (d) case studies using auditory-perceptual and acoustic-phonetic methods to describe intelligibility differences in children with speech delays before, during, and after episodes of OME; and (e) longitudinal studies to determine the course of normalization from 3-6 years of intelligibility deficits associated with early recurrent OME.